My bare bookshelves are crying out for the addition of a new family member, more specifically a book:
Discussing the classical Klein-Gordon field, spinor fields, gauge fields and all other matter fields in a generally co-variant fashion.
Discussing of the Schrodinger (non-relativistic scalar) field.
Detailing the application of fields to things like inflation, dark matter, condensed matter etc.
Possessing nice, thorough derivations (like the single-particle, relativistic Lagrangians from the complex scalar field) and other such items of interest which show how single-particle mechanics follow from classical fields. Discussion of conformal symmetries, first class and second class constraints are also desired.
With some discussion of field quantization.
I have possession of some papers covering these topics and some books (like Landau's Classical Theory of Fields), but they are outdated, restricted to EM fields and very often bypass all discussion of classical fields to quantize them right away. Since I asked for a generally co-variant approach, there should be extensive co-ordinate free representations.